Corticotropin releasing factor (herein referred to as CRF), a 41 amino acid peptide, is the primary physiological regulator of proopiomelanocortin (POMC)-derived peptide secretion from the anterior pituitary gland [J. Rivier et al., Proc. Nat. Acad. Sci. (USA) 80:4851 (1983); W. Vale et al., Science 213:1394 (1981)]. In addition to its endocrine role at the pituitary gland, immunohistochemical localization of CRF has demonstrated that the hormone has a broad extrahypothalamic distribution in the central nervous system and produces a wide spectrum of autonomic, electrophysiological and behavioral effects consistent with a neurotransmitter or neuromodulator role in brain [W. Vale et al., Rec. Prog. Horm. Res. 39:245 (1983); G. F. Koob, Persp. Behav. Med. 2:39 (1985); E. B. De Souza et al., J. Neurosci. 5:3189 (1985)]. There is also evidence that CRF plays a significant role in integrating the response of the immune system to physiological, psychological, and immunological stressors [J. E. Blalock, Physiological Reviews 69:1 (1989); J. E. Morley, Life Sci. 41:527 (1987)].
Clinical data provide evidence that CRF has a role in psychiatric disorders and neurological diseases including depression, anxiety-related disorders and feeding disorders. A role for CRF has also been postulated in the etiology and pathophysiology of Alzheimer's disease, Parkinson's disease, Huntington's disease, progressive supranuclear palsy and amyotrophic lateral sclerosis as they relate to the dysfunction of CRF neurons in the central nervous system [for review see E. B. De Souza, Hosp. Practice 23:59 (1988)].
In affective disorder, or major depression, the concentration of CRF is significantly increased in the cerebral spinal fluid (CSF) of drug-free individuals [C. B. Nemeroff et al., Science 226:1342 (1984); C. M. Banki et al., Am. J. Psychiatry 144:873 (1987); R. D. France et al., Biol. Psychiatry 28:86 (1988); M. Arato et al., Biol Psychiatry 25:355 (1989)]. Furthermore, the density of CRF receptors is significantly decreased in the frontal cortex of suicide victims, consistent with a hypersecretion of CRF [C. B. Nemeroff et al., Arch. Gen. Psychiatry 45:577 (1988)]. In addition, there is a blunted adrenocorticotropin (ACTH) response to CRF (i.v. administered) observed in depressed patients [P. W. Gold et al., Am J. Psychiatry 141:619 (1984); F. Holsboer et al., Psychoneuroendocrinology 9:147 (1984); P. W. Gold et al., New Eng. J. Med. 314:1129 (1986)]. Preclinical studies in rats and non-human primates provide additional support for the hypothesis that hypersecretion of CRF may be involved in the symptoms seen in human depression [R. M. Sapolsky, Arch. Gen. Psychiatry 46:1047 (1989)]. There is preliminary evidence that tricyclic antidepressants can alter CRF levels and thus modulate the numbers of CRF receptors in brain [Grigoriadis et al., Neuropsychopharmacology 2:53 (1989)].
There has also been a role postulated for CRF in the etiology of anxiety-related disorders. CRF produces anxiogenic effects in animals and interactions between benzodiazepine/non-benzodiazepine anxiolytics and CRF have been demonstrated in a variety of behavioral anxiety models [D. R. Britton et al., Life Sci. 31:363 (1982); C. W. Berridge and A. J. Dunn Regul. Peptides 16:83 (1986)]. Preliminary studies using the putative CRF receptor antagonist a-helical ovine CRF (9-41) in a variety of behavioral paradigms demonstrate that the antagonist produces “anxiolytic-like” effects that are qualitatively similar to the benzodiazepines [C. W. Berridge and A. J. Dunn Horm. Behav. 21:393 (1987), Brain Research Reviews 15:71 (1990)]. Neurochemical, endocrine and receptor binding studies have all demonstrated interactions between CRF and benzodiazepine anxiolytics providing further evidence for the involvement of CRF in these disorders. Chlordiazepoxide attenuates the “anxiogenic” effects of CRF in both the conflict test [K. T. Britton et al., Psychopharmacology 86:170 (1985); K. T. Britton et al., Psychopharmacology 94:306 (1988)] and in the acoustic startle test [N. R. Swerdlow et al., Psychopharmacology 88:147 (1986)] in rats. The benzodiazepine receptor antagonist (Ro15-1788), which was without behavioral activity alone in the operant conflict test, reversed the effects of CRF in a dose-dependent manner while the benzodiazepine inverse agonist (FG7142) enhanced the actions of CRF [K. T. Britton et al., Psychopharmacology 94:306 (1988)].
The mechanisms and sites of action through which the standard anxiolytics and antidepressants produce their therapeutic effects remain to be elucidated. It has been hypothesized however, that they are involved in the suppression of the CRF hypersecretion that is observed in these disorders. Of particular interest is that preliminary studies examining the effects of a CRF receptor antagonist (α-helical CRF 9-41) in a variety of behavioral paradigms have demonstrated that the CRF antagonist produces “anxiolytic-like” effects qualitatively similar to the benzodiazepines [for review see G. F. Koob and K. T. Britton, In: Corticotropin-Releasing Factor: Basic and Clinical Studies of a Neuropeptide, E. B. De Souza and C. B. Nemeroff eds., CRC Press p 221 (1990)].
Several publications describe corticotropin releasing factor antagonist compounds and their use to treat psychiatric disorders and neurological diseases. Examples of such publications include DuPont Merck PCT application US94/11050, Pfizer WO 95/33750, Pfizer WO 95/34563, Pfizer WO 95/33727 and Pfizer EP 0778 277 A1.
Insofar as is known, [1,5-a]-pyrazolo-1,3,5-triazines, [1,5-a]-1,2,3-triazolo-1,3,5-triazines, [1,5-a]-pyrazolo-pyrimidines and [1,5-a]-1,2,3-triazolo-pyrimidines, have not been previously reported as corticotropin releasing factor antagonist compounds useful in the treatment of psychiatric disorders and neurological diseases. However, there have been publications which teach some of these compounds for other uses.
For instance, EP 0 269 859 (Ostuka, 1988) discloses pyrazolotriazine compounds of the formula:
where R1 is OH or alkanoyl, R2 is H, OH, or SH, and R3 is an unsaturated heterocyclic group, naphthyl or substituted phenyl, and states that the compounds have xanthine oxidase inhibitory activity and are useful for treatment of gout.
EP 0 594 149 (Ostuka, 1994) discloses pyrazolotriazine and pyrazolopyrimidine compounds of the formula:
where A is CH or N, R0 and R3 are H or alkyl, and R1 and R2 are H, alkyl, alkoxyl, alkylthio, nitro, etc., and states that the compounds inhibit androgen and are useful in treatment of benign prostatic hypertrophy and prostatic carcinoma.
U.S. Pat. No. 3,910,907 (ICI, 1975) discloses pyrazolotriazines of the formula:
where R1 is CH3, C2H5 or C6H5, X is H, C6H5, m-CH3C6H4, CN, COOEt, Cl, I or Br, Y is H, C6H5, o-CH3C6H4, or p-CH3C6H4, and Z is OH, H, CH3, C2H5, C6H5, n-C3H7, i-C3H7, SH, SCH3, NHC4H9, or N(C2H5)2, and states that the compounds are c-AMP phosphodiesterase inhibitors useful as bronchodilators.
U.S. Pat. No. 3,995,039 discloses pyrazolotriazines of the formula:
where R1 is H or alkyl, R2 is H or alkyl, R3 is H, alkyl, alkanoyl, carbamoyl, or lower alkylcarbamoyl, and R is pyridyl, pyrimidinyl, or pyrazinyl, and states that the compounds are useful as bronchodilators.
U.S. Pat. No. 5,137,887 discloses pyrazolotriazines of the formula:
where R is lower alkoxy, and teaches that the compounds are xanthine oxidase inhibitors and are useful for treatment of gout.
U.S. Pat. No. 4,892,576 discloses pyrazolotriazines of the formula:
where X is O or S, Ar is a phenyl, naphthyl, pyridyl or thienyl group, R6-R8 are H, alkyl, etc., and R9 is H, alkyl, phenyl, etc. The patent states that the compounds are useful as herbicides and plant growth regulants.
U.S. Pat. No. 5,484,760 and WO 92/10098 discloses herbicidal compositions containing, among other things, a herbicidal compound of the formula:
where A can be N, B can be CR3, R3 can be phenyl or substituted phenyl, etc., R is —N(R4)SO2R5 or —SO2N(R6)R7 and R1 and R2 can be taken together to form
where X, Y and Z are H, alkyl, acyl, etc. and D is O or S.
U.S. Pat. No. 3,910,907 and Senga et al., J. Med. Chem., 1982, 25, 243-249, disclose triazolotriazines cAMP phosphodiesterase inhibitors of the formula:
where Z is H, OH, CH3, C2H5, C6H5, n-C3H7, iso-C3H7, SH, SCH3, NH(n-C4H9), or N(C2H5)2, R is H or CH3, and R1 is CH3 or C2H5. The reference lists eight therapeutic areas where inhibitors of cAMP phosphodiesterase could have utility: asthma, diabetes mellitus, female fertility control, male infertility, psoriasis, thrombosis, anxiety, and hypertension.
WO95/35298 (Otsuka, 1995) discloses pyrazolopyrimidines and states that they are useful as analgesics. The compounds are represented by the formula:
where Q is carbonyl or sulfonyl, n is 0 or 1, A is a single bond, alkylene or alkenylene, R1 is H, alkyl, etc., R2 is naphthyl, cycloalkyl, heteroaryl, substituted phenyl or phenoxy, R3 is H, alkyl or phenyl, R4 is H, alkyl, alkoxycarbonyl, phenylalkyl, optionally phenylthio-substituted phenyl, or halogen, R5 and R6 are H or alkyl.
EP 0 591 528 (Otsuka, 1991) discloses anti-inflammatory use of pyrazolopyrimidines represented by the formula:
where R1, R2, R3 and R4 are H, carboxyl, alkoxycarbonyl, optionally substituted alkyl, cycloalkyl, or phenyl, R5 is SR6 or NR7R8, R6 is pyridyl or optionally substituted phenyl, and R7 and R8 are H or optionally substituted phenyl.
Springer et al, J. Med. Chem., 1976, vol. 19, no. 2, 291-296 and Springer U.S. Pat. Nos. 4,021,556 and 3,920,652 disclose pyrazolopyrimidines of the formula:
where R can be phenyl, substituted phenyl or pyridyl, and their use to treat gout, based on their ability to inhibit xanthine oxidase.
Joshi et al., J. Prakt. Chemie, 321, 2, 1979, 341-344, discloses compounds of the formula:
where R1 is CF3, C2F5, or C6H4F, and R2 is CH3, C2H5, CF3, or C6H4F.
Maquestiau et al., Bull. Soc. Belg., vol. 101, no. 2, 1992, pages 131-136 discloses a pyrazolo[1,5-a]pyrimidine of the formula:

Ibrahim et al., Arch. Pharm. (weinheim) 320, 487-491 (1987) discloses pyrazolo[1,5-a]pyrimidines of the formula:
where R is NH2 or OH and Ar is 4-phenyl-3-cyano-2-aminopyrid-2-yl.
Other references which disclose azolopyrimidines included EP 0 511 528 (Otsuka, 1992), U.S. Pat. No. 4,997,940 (Dow, 1991), EP 0 374 448 (Nissan, 1990), U.S. Pat. No. 4,621,556 (ICN, 1997), EP 0 531 901 (Fujisawa, 1993), U.S. Pat. No. 4,567,263 (BASF, 1986), EP 0 662 477 (Isagro, 1995), DE 4 243 279 (Bayer, 1994), U.S. Pat. No. 5,397,774 (Upjohn, 1995), EP 0 521 622 (Upjohn, 1993), WO 94/109017 (Upjohn, 1994), J. Med. Chem., 24, 610-613 (1981), and J. Het. Chem., 22, 601 (1985).